1. Field of the Invention
The present invention relates to a PM emission estimation device for estimating the emission amount of the PM (Particulate Matter) in the exhaust gas emitted from a diesel engine.
2. Background of the Invention
Patent Reference 1 (JP2007-23959) discloses a technology regarding a PM emission estimation device for estimating the emission amount of the PM (Particulate Matter) in the exhaust gas emitted from a diesel engine.
In the disclosure of Patent Reference 1, as shown In FIG. 14, the block diagram regarding the PM emission estimation device is configured with:                a PM emission amount estimation map 01 by which the basic level of the PM emission amount is computed based on the engine speed Ne and the fuel injection quantity Qf as the variables with regard to the engine operation condition;        a PM emission amount estimation correction factor map 03 by which the correction factor for correcting the PM emission amount estimation is computed by use of the difference (rλ−tλ) between the actual air excess ratio rλ and the target air excess ratio tλ, or by use of the ratio (rλ/tλ) of the actual air excess ratio rλ to the target air excess ratio tλ, the target air excess ratio tλ and the actual air excess ratio rλ being set as the first parameter PA and the second parameter PB, respectively,        
wherein                the emission amount of the PM is computed by multiplying the basic level of the PM emission amount obtained by use of the PM emission amount estimation map 01 by the correction factor computed by use of the PM emission amount estimation correction factor map 03.        
Further, the corrected PM emission amount having been corrected by use of the correction factor is integrated at the an integrator (an integration section) 07 so that the amount of the PM which is accumulated in a DPF (Diesel Particulate Filter) provided in the exhaust gas passage of a diesel engine is estimated, the DPF being provided for collecting the PM.